THOMAS "Tommy Gun" Oosthuizen says he is raring to go as he prepares to climb in the ring for his International Boxing Organisation (IBO) supermiddleweight title defence against Mexican Francisco Sierra at Emperors Palace on Wednesday.

"Preparations for this fight have been going really well," Oosthuizen said over the weekend.

"Technique-wise there is a lot of improvement and stuff, my hand speed is very good and everything is just picking up so nicely. I'm peaking at the right time for this fight, I'm ready for this fight, and I will not fall asleep in the ring."

The 23-year-old southpaw is fresh off an imposing victory over Aaron Pryor in Biloxi, Mississippi, in early September.

Oosthuizen will go into the fight against the Mexican with possible future fights in the US weighing heavily on his mind.

Golden Gloves promoter Rodney Berman said at the pre-fight medical for their Grand Slam tournament that there had been great interest for Oosthuizen out of America, and this fight could provide a huge step in his career.

Oosthuizen's challenger, ranked 23rd by the IBO, has 22 knockouts in 24 wins from 27 fights, and the South African has a tough battle to overcome Sierra.

Earlier on the Grand Slam bill, Sipho Taliwe defends his World Boxing Council (WBC) international junior-lightweight title against Jasper Seroke - the third time the two boxers will meet.